Isotopes of cobalt

Isotopes of cobalt (₂₇Co)
Standard atomic weight Ar°(Co)
	58.933194±0.000003; 58.933±0.001 (abridged);
	view; talk; edit;

Naturally occurring cobalt, Co, consists of a single stable isotope, ⁵⁹Co (thus, cobalt is a mononuclidic element). Twenty-eight radioisotopes have been characterized; the most stable are ⁶⁰Co with a half-life of 5.2714 years, ⁵⁷Co (271.8 days), ⁵⁶Co (77.27 days), and ⁵⁸Co (70.86 days). All other isotopes have half-lives of less than 18 hours and most of these have half-lives of less than 1 second. This element also has 11 meta states, all of which have half-lives of less than 15 minutes.

The isotopes of cobalt range in atomic weight from ⁴⁷Co to ⁷⁵Co. The main decay mode for isotopes with atomic mass less than that of the stable isotope, ⁵⁹Co, is electron capture and the main mode of decay for those of greater than 59 atomic mass units is beta decay. The main decay products before ⁵⁹Co are iron isotopes and the main products after are nickel isotopes.

Radioisotopes can be produced by various nuclear reactions. For example, ⁵⁷Co is produced by cyclotron irradiation of iron. The main reaction is the (d,n) reaction ⁵⁶Fe + ²H → n + ⁵⁷Co.^[4]

List of isotopes

Nuclide ^{[n 1]}	Z	N	Isotopic mass (Da) ^{[n 2]}^{[n 3]}	Half-life ^{[n 4]}	Decay mode ^{[n 5]}	Daughter isotope ^{[n 6]}	Spin and parity ^{[n 7]}^{[n 4]}	Isotopic abundance
Nuclide ^{[n 1]}	Excitation energy^{[n 4]}			Half-life ^{[n 4]}	Decay mode ^{[n 5]}	Daughter isotope ^{[n 6]}	Spin and parity ^{[n 7]}^{[n 4]}	Isotopic abundance
⁴⁷Co	27	20	47.01149(54)#				7/2−#
⁴⁸Co	27	21	48.00176(43)#		p	⁴⁷Fe	6+#
⁴⁹Co	27	22	48.98972(28)#	<35 ns	p (>99.9%)	⁴⁸Fe	7/2−#
⁴⁹Co	27	22	48.98972(28)#	<35 ns	β⁺ (<.1%)	⁴⁹Fe	7/2−#
⁵⁰Co	27	23	49.98154(18)#	44(4) ms	β⁺, p (54%)	⁴⁹Mn	(6+)
⁵⁰Co	27	23	49.98154(18)#	44(4) ms	β⁺ (46%)	⁵⁰Fe	(6+)
⁵¹Co	27	24	50.97072(16)#	60# ms [>200 ns]	β⁺	⁵¹Fe	7/2−#
⁵²Co	27	25	51.96359(7)#	115(23) ms	β⁺	⁵²Fe	(6+)
^52mCo	380(100)# keV			104(11)# ms	β⁺	⁵²Fe	2+#
^52mCo	380(100)# keV			104(11)# ms	IT	⁵²Co	2+#
⁵³Co	27	26	52.954219(19)	242(8) ms	β⁺	⁵³Fe	7/2−#
^53mCo	3197(29) keV			247(12) ms	β⁺ (98.5%)	⁵³Fe	(19/2−)
^53mCo	3197(29) keV			247(12) ms	p (1.5%)	⁵²Fe	(19/2−)
⁵⁴Co	27	27	53.9484596(8)	193.28(7) ms	β⁺	⁵⁴Fe	0+
^54mCo	197.4(5) keV			1.48(2) min	β⁺	⁵⁴Fe	(7)+
⁵⁵Co	27	28	54.9419990(8)	17.53(3) h	β⁺	⁵⁵Fe	7/2−
⁵⁶Co	27	29	55.9398393(23)	77.233(27) d	β⁺	⁵⁶Fe	4+
⁵⁷Co	27	30	56.9362914(8)	271.74(6) d	EC	⁵⁷Fe	7/2−
⁵⁸Co	27	31	57.9357528(13)	70.86(6) d	β⁺	⁵⁸Fe	2+
^58m1Co	24.95(6) keV			9.04(11) h	IT	⁵⁸Co	5+
^58m2Co	53.15(7) keV			10.4(3) μs			4+
⁵⁹Co	27	32	58.9331950(7)	Stable			7/2−	1.0000
⁶⁰Co	27	33	59.9338171(7)	5.2714(6) y	β⁻, γ	⁶⁰Ni	5+
^60mCo	58.59(1) keV			10.467(6) min	IT (99.76%)	⁶⁰Co	2+
^60mCo	58.59(1) keV			10.467(6) min	β⁻ (.24%)	⁶⁰Ni	2+
⁶¹Co	27	34	60.9324758(10)	1.650(5) h	β⁻	⁶¹Ni	7/2−
⁶²Co	27	35	61.934051(21)	1.50(4) min	β⁻	⁶²Ni	2+
^62mCo	22(5) keV			13.91(5) min	β⁻ (99%)	⁶²Ni	5+
^62mCo	22(5) keV			13.91(5) min	IT (1%)	⁶²Co	5+
⁶³Co	27	36	62.933612(21)	26.9(4) s	β⁻	⁶³Ni	7/2−
⁶⁴Co	27	37	63.935810(21)	0.30(3) s	β⁻	⁶⁴Ni	1+
⁶⁵Co	27	38	64.936478(14)	1.20(6) s	β⁻	⁶⁵Ni	(7/2)−
⁶⁶Co	27	39	65.93976(27)	0.18(1) s	β⁻	⁶⁶Ni	(3+)
^66m1Co	175(3) keV			1.21(1) μs			(5+)
^66m2Co	642(5) keV			>100 μs			(8-)
⁶⁷Co	27	40	66.94089(34)	0.425(20) s	β⁻	⁶⁷Ni	(7/2−)#
⁶⁸Co	27	41	67.94487(34)	0.199(21) s	β⁻	⁶⁸Ni	(7-)
^68mCo	150(150)# keV			1.6(3) s			(3+)
⁶⁹Co	27	42	68.94632(36)	227(13) ms	β⁻ (>99.9%)	⁶⁹Ni	7/2−#
⁶⁹Co	27	42	68.94632(36)	227(13) ms	β⁻, n (<.1%)	⁶⁸Ni	7/2−#
⁷⁰Co	27	43	69.9510(9)	119(6) ms	β⁻ (>99.9%)	⁷⁰Ni	(6-)
⁷⁰Co	27	43	69.9510(9)	119(6) ms	β⁻, n (<.1%)	⁶⁹Ni	(6-)
^70mCo	200(200)# keV			500(180) ms			(3+)
⁷¹Co	27	44	70.9529(9)	97(2) ms	β⁻ (>99.9%)	⁷¹Ni	7/2−#
⁷¹Co	27	44	70.9529(9)	97(2) ms	β⁻, n (<.1%)	⁷⁰Ni	7/2−#
⁷²Co	27	45	71.95781(64)#	62(3) ms	β⁻ (>99.9%)	⁷²Ni	(6- ,7-)
⁷²Co	27	45	71.95781(64)#	62(3) ms	β⁻, n (<.1%)	⁷¹Ni	(6- ,7-)
⁷³Co	27	46	72.96024(75)#	41(4) ms			7/2−#
⁷⁴Co	27	47	73.96538(86)#	50# ms [>300 ns]			0+
⁷⁵Co	27	48	74.96833(86)#	40# ms [>300 ns]			7/2−#
⁷⁶Co^[5]	27	49		40# ms	β^-	⁷⁶Ni	8-#
This table header & footer: view

^ ^mCo – Excited nuclear isomer.
^ ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
^ # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
^ ^a ^b ^c # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
^ Modes of decay:

EC: Electron capture

IT: Isomeric transition

n: Neutron emission

p: Proton emission
^ Bold symbol as daughter – Daughter product is stable.
^ ( ) spin value – Indicates spin with weak assignment arguments.

Stellar nucleosynthesis of cobalt-56

One of the terminal nuclear reactions in stars prior to supernova produces ⁵⁶Ni. Following its production, ⁵⁶Ni decays to ⁵⁶Co, and then ⁵⁶Co subsequently decays to ⁵⁶Fe. These decay reactions power the luminosity displayed in light decay curves. Both the light decay and radioactive decay curves are expected to be exponential. Therefore, the light decay curve should give an indication of the nuclear reactions powering it. This has been confirmed by observation of bolometric light decay curves for SN 1987A. Between 600 and 800 days after SN1987A occurred, the bolometric light curve decreased at an exponential rate with half-life values from τ_1/2 = 68.6 days to τ_1/2 = 69.6 days.^[6] The rate at which the luminosity decreased closely matched the exponential decay of ⁵⁶Co with a half-life of τ_1/2 = 77.233 days.

Use of cobalt radioisotopes in medicine

Cobalt-57 (⁵⁷Co or Co-57) is used in medical tests; it is used as a radiolabel for vitamin B₁₂ uptake. It is useful for the Schilling test.^[7]

Cobalt-60 (⁶⁰Co or Co-60) is used in radiotherapy. It produces two gamma rays with energies of 1.17 MeV and 1.33 MeV. The ⁶⁰Co source is about 2 cm in diameter and as a result produces a geometric penumbra, making the edge of the radiation field fuzzy. The metal has the unfortunate habit of producing fine dust, causing problems with radiation protection. The ⁶⁰Co source is useful for about 5 years but even after this point is still very radioactive, and so cobalt machines have fallen from favor in the Western world where Linacs are common.

Industrial uses for radioactive isotopes

Cobalt-60 (⁶⁰Co) is useful as a gamma ray source because it can be produced in predictable quantities, and for its high radioactivity simply by exposing natural cobalt to neutrons in a reactor.^[8] The uses for industrial cobalt include:

Sterilization of medical supplies and medical waste
Radiation treatment of foods for sterilization (cold pasteurization)^[9]
Industrial radiography (e.g., weld integrity radiographs)
Density measurements (e.g., concrete density measurements)
Tank fill height switches

⁵⁷Co is used as a source in Mössbauer spectroscopy of iron-containing samples. Electron capture by ⁵⁷Co forms an excited state of the ⁵⁷Fe nucleus, which in turn decays to the ground state with the emission of a gamma ray. Measurement of the gamma-ray spectrum provides information about the chemical state of the iron atom in the sample.

References

^ Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.
^ "Standard Atomic Weights: Cobalt". CIAAW. 2017.
^ Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; Böhlke, John K.; Chesson, Lesley A.; Coplen, Tyler B.; Ding, Tiping; Dunn, Philip J. H.; Gröning, Manfred; Holden, Norman E.; Meijer, Harro A. J. (2022-05-04). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.
^ Diaz, L. E. "Cobalt-57: Production". JPNM Physics Isotopes. University of Harvard. Archived from the original on 2000-10-31. Retrieved 2013-11-15.
^ Ohnishi, Tetsuya; Kubo, Toshiyuki; Kusaka, Kensuke; et al. (2010). "Identification of 45 New Neutron-Rich Isotopes Produced by In-Flight Fission of a ²³⁸U Beam at 345 MeV/nucleon". J. Phys. Soc. Jpn. 79 (7). Physical Society of Japan: 073201. arXiv:1006.0305. Bibcode:2010JPSJ...79g3201T. doi:10.1143/JPSJ.79.073201.
^ Bouchet, P.; Danziger, I.J.; Lucy, L.B. (September 1991). "Bolometric Light Curve of SN 1987A: Results from Day 616 to 1316 After Outburst". The Astronomical Journal. 102 (3): 1135–1146 – via Astrophysics Data System.
^ Diaz, L. E. "Cobalt-57: Uses". JPNM Physics Isotopes. University of Harvard. Archived from the original on 2011-06-11. Retrieved 2010-09-13.
^ "Properties of Cobalt-60". Radioactive Isotopes. Retrieved 2022-12-09.
^ "Beneficial Uses of Cobalt-60". INTERNATIONAL IRRADIATION ASSOCIATION. Retrieved 2022-12-09.

Isotope masses from:
- Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001
Half-life, spin, and isomer data selected from the following sources.
- Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001
- National Nuclear Data Center. "NuDat 2.x database". Brookhaven National Laboratory.
- Holden, Norman E. (2004). "11. Table of the Isotopes". In Lide, David R. (ed.). CRC Handbook of Chemistry and Physics (85th ed.). Boca Raton, Florida: CRC Press. ISBN 978-0-8493-0485-9.

[5] Co – Excited nuclear isomer.

[6] ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.

[TMS-7] # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).

[TNN-8] # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).

[9] Modes of decay:

EC: Electron capture

IT: Isomeric transition

n: Neutron emission

p: Proton emission

[10] Bold symbol as daughter – Daughter product is stable.

[11] ( ) spin value – Indicates spin with weak assignment arguments.

[NUBASE2020-1] Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.

[2] "Standard Atomic Weights: Cobalt". CIAAW. 2017.

[CIAAW2021-3] Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; Böhlke, John K.; Chesson, Lesley A.; Coplen, Tyler B.; Ding, Tiping; Dunn, Philip J. H.; Gröning, Manfred; Holden, Norman E.; Meijer, Harro A. J. (2022-05-04). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.

[57Co-Diaz-production-4] Diaz, L. E. "Cobalt-57: Production". JPNM Physics Isotopes. University of Harvard. Archived from the original on 2000-10-31. Retrieved 2013-11-15.

[Ohnishi-12] Ohnishi, Tetsuya; Kubo, Toshiyuki; Kusaka, Kensuke; et al. (2010). "Identification of 45 New Neutron-Rich Isotopes Produced by In-Flight Fission of a ²³⁸U Beam at 345 MeV/nucleon". J. Phys. Soc. Jpn. 79 (7). Physical Society of Japan: 073201. arXiv:1006.0305. Bibcode:2010JPSJ...79g3201T. doi:10.1143/JPSJ.79.073201.

[13] Bouchet, P.; Danziger, I.J.; Lucy, L.B. (September 1991). "Bolometric Light Curve of SN 1987A: Results from Day 616 to 1316 After Outburst". The Astronomical Journal. 102 (3): 1135–1146 – via Astrophysics Data System.

[57Co-Diaz-uses-14] Diaz, L. E. "Cobalt-57: Uses". JPNM Physics Isotopes. University of Harvard. Archived from the original on 2011-06-11. Retrieved 2010-09-13.

[15] "Properties of Cobalt-60". Radioactive Isotopes. Retrieved 2022-12-09.

[16] "Beneficial Uses of Cobalt-60". INTERNATIONAL IRRADIATION ASSOCIATION. Retrieved 2022-12-09.

[1]

[2]

[3]

[4]

[n 1]

[n 2]

[n 3]

[n 4]

[n 5]

[n 6]

[n 7]

[5]

[6]

[7]

[8]

[9]